The present invention relates to golf ball compression molds such as those described in U.S. Pat. Nos. 4,508,309 and 4,558,499, which issued to Brown and are assigned to the Acushnet Company and co-pending U.S. application Ser. No. 08/455,442 which is assigned to the Acushnet Company. The prior art compression molding presses use mold frames secured to steel plates. Within each mold frame is disposed a plurality of cavities. Each cavity accommodates a golf ball half-mold. The golf ball half-molds are disposed in a closely packed arrangement within each frame. Each golf ball half-mold is substantially located horizontally by the cavities in the frames.
In the prior art molds, the mold frames were attached to steel plates to secure and locate them in the compression mold. The golf ball half-molds are located in the frame cavities and would abut against the steel plates. Thus, the steel plates of the prior art molds located the half-molds in the vertical direction. The steel plates, which are located on thermal insulators and press platens, tend to have irregularities and variations such as low and high spots which cause "out-of-flatness" conditions. The steel plates, thermal insulators, and platens will be referred to collectively hereafter as the press assembly. While the out-of-flatness may be minimal, the undulations in the press assembly can cause the half-molds to be located at different vertical positions and mate improperly with the opposing or corresponding half-mold. When the mold is compressed to form a golf ball, the different vertical positions of the half-molds can create unwanted size variations of the golf balls. Out-of-flatness can also cause the half-molds to be misaligned during compression of the press. For example, the out-of-flatness condition causes corresponding half-molds that are on "high" spots to meet first when the mold is closed and can leave gaps between half-molds that are located on "low" spots. These gaps allow excess molding material to escape the mold and form around the golf ball, which hinders the golf ball from properly releasing from the mold frame after formation. In order to get the golf ball to release from the frame, excessive force must be used to push the ball from the mold. This can cause a marking of the ball and injury to the operator. In addition, the excess molding material surrounding the ball can result in undesired size variations between golf balls.
An object of this invention is to reduce the out-of-flatness condition associated with the current compression molding process caused by the irregularities of the press assembly. This, in turn, will improve the release of the golf ball from the mold and improve the size stability and uniformity of the molded golf balls.